Why don't boats have gears?

Discussion in 'DIY Marinizing' started by jakefrith, Oct 28, 2008.

  1. nukisen
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    nukisen Senior Member

    Sorry for the spelling and grammer.
     
  2. Aharon
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    Aharon Junior Member

    Nukisen, your ideas are way much important than spelling and grammar. Do not worry about them, just keep those ideas and suggestions coming.
    I am a beginner myself, planning to build my first boat at age 56, and I never cease to marvel at the lenght people here will go to discuss any subject brought to light.
    BDnet is like a "free university" where I can ask stupid questions and still be respected.
    Way to go, you Swedish Seaman!
    Aharon, from sunny Israel.
     
  3. nukisen
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    nukisen Senior Member

    :)!
    A boatdesigner and builder is always respected! :)
     
  4. Lurvio
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    Lurvio Mad scientist

    I have been toyin with these ideas at some point myself. One thing you guys are forgetting (especially torque converters) are losses in the extra parts. With a slipping TC you probably won't get any more hp to the prop as the power is being churned in to heat in the converter.

    What I've been thinking (for an inboard runabout type boat) is to use a basic car automatic trans without the torque converter. Stripping the TC you basically get a powershift trans with reverse, wet multidisc clutches on all gears. My thinking was that I might want to use the mean machine for trolling at some point and the engine idle might be too much speed for the poor little piece of balsawood and hooks at the end of the line.

    Just my 2c worth. :)
    Lurvio
     
  5. whitepointer23

    whitepointer23 Previous Member

    a company in melbourne used to sell auto's for marine use in the 80's. they used a 2 speed gm powerglide automatic with out the torque convertor and tailshaft housing. it was a neat looking unit. quite compact but a fairly complicated job to do your self unless you have access to machining equipment.
     
  6. powerabout
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    powerabout Senior Member

    Art Carr transmissions in the the US has been doing this for more than 30 years
     
  7. powerabout
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    powerabout Senior Member

    One problem you need to solve is to stop the prop from rotating when in neutral due to the drag inside the box.
     
  8. Lurvio
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    Lurvio Mad scientist

    Don't a car gearbox have a park gear, which locks the trans output? Maybe not all of them, but at least the ones I have seen used.

    I have a couple of old Borg/Aisin Wagner autos lying around, maybe I should check what could be done with them. I have skill and some machinery which might come in handy in such conversion. :)

    Lurvio

    Edit: Borg Warner, Wagner is (among other things), a pig starring in a Finnish comic strip.
     
  9. nukisen
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    nukisen Senior Member

    Very easy to solve this!
    exchange the convertor to a centrifugal clutch. Then the problem is no problem any more.
    All you have to do is to put throttle to idle.
    Even used in very modern cars nowadays. Also with cvh gears.
    All parts already invented. just convert the output to prop axle instead of driveshaft.
     
  10. whitepointer23

    whitepointer23 Previous Member

    yes you can use park , i have driven my friends boats with full auto trans and he uses the park function. you don't need an anchor , just put it in park.
     
  11. powerabout
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    powerabout Senior Member

    yes simple and you would put every marine transmission builder out of work
    shock horror but nobody makes what you suggest, theres your answer
     
  12. whitepointer23

    whitepointer23 Previous Member

    glen l tornado with powerglide auto and cassale v drive.
     

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  13. Lurvio
    Joined: Jul 2009
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    Lurvio Mad scientist

    A centrifugal clutch came to my mind also, but if the park does not lock input shaft as I don't think it does, there really is no need for it.

    Centrifugal clutch is pretty easy to design and make, just need a couple of parts machined. Just made one about a year ago, works like a charm, has a brake drum from a Ford Transit truck (pair wheels in the back). My dad skimped on the springs strenght, so it connects under idle speed, but that works fine for the application it's in.

    Lurvio
     
  14. whitepointer23

    whitepointer23 Previous Member

    park only locks output shaft
     

  15. DCockey
    Joined: Oct 2009
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    DCockey Senior Member

    What would be gained by using a centrifugal clutch in a boat?
     
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